Method of glass coating metal members



March8, 1960 R. M. HORTVET 2,927,869

METHOD OF GLASS COATING METAL MEMBERS Filed Dec. 51, 1956 2 Sheets- Sheet 1 INVENTOR :Xfiornegs RICHARD M. H URTVE'T APPLY/N6 GLASS FRIT ll Y

STORAGE 0R ASSEMBLY R. M. HORTVET METHOD OF GLASS COATING METAL MEMBERS March 8, 1960 2 Sheets-Sheet 2 Filed D90. 51, 1956 INVENTOR.

S uat/Jays METHOD OF GLASS COATING METAL MEMBERS Richard M. Hortvet, Milwaukee, Wis., assignor to A. O. Smith Corporation, Milwaukee, Wis., a corporation of New York Application December 31, 1956, Serial No. 631,912

4 Claims. (Cl. 117-94) This invention relates to a method and apparatus for glass coating metal members and particularly heavy metal members such as steel chimney sections and the like.

It is often desirable to glass coat the surface of tubular metal members such as chimneys to prevent corrosion of the metal surface. To fuse the glass to the metal members, they are heated to a relatively high temperature which changes the metal to a somewhat plastic state. The metal then tends to flow and thereby deforms the member. This is particularly true if the member is fired while held in a vertical position resting on a base support because during the firing of the lower portion of the member the weight of the member above the heated area causes the heated metal to sag or flow.

in accordance with the present invention, the memher is disposed in an upright position resting on a base support. The member is then progressively fired from the top downwardly, preferably by a continuously moving heat source. As the heat source leaves the top of the member, the top portion of the member cools. A lifting force is then applied to the upper cooled portion of the member to take up a portion of the Weight of the member and thus relieve the lower portions of the member of a portion of the entire weight during the firing thereof.

The present invention is particularly adapted to the firing of chimney sections which are coated with glass on both the interior and the exterior surface. The chimney sections are formed with lateral flanges encircling the upper and lower end of the chimney sections for securing the sections together. A lifting mechanism engages the upper flange to take up a portion of the weight when firing the lower portion of the chimney. As the flanges are employed for mounting and are not normally glass coated they may readily be engaged by a suitable lifting mechanism without damaging the glass coating on the chimney section.

The accompanying drawings illustrate the best mode presently contemplated by the inventor for carrying out the invention.

In the drawings:

Figure 1 is a perspective view of a chimney section with parts broken away to show the glass coating;

Fig. 2 is a flow diagram showing the steps followed in glass coating a chimney section;

Fig. 3 is a vertical section through a firing station with a chimney section support therein;

Fig. 4- is a view taken on line 4--4 of Fig. 3;

Fig. 5 is a view taken on line 55 of Fig. 3; and

Fig. 6 is a view taken on line 6-6 of Fig. 3.

Referring to the drawings and particularly Fig. 1, a tubular metal chimney section 1 is provided with an upper mounting flange 2 and a lower mounting flange 3. Suitable apertures 4 are provided in each of the flanges 2 and 3 for securingv a plurality of the sections 1 by bolts or the like in stacked relation. A glass coating 5 covers the interior surface of each chimney secnited States Patent 0 g 2,927,869 Patented Mar. 8, 1969 tion and a similar glass coating 6 covers the exterior surface of each chimney section to prevent corrosion of the metal.

Referring to the flow diagram in Fig. 2, the chimney section 1 is first taken to a cleaning station 7 to prepare the base metal for glass coating by sand blasting or other suitable process. From the cleaning station 7 the chimney section is transferred to a slushing station 8 where the inside surface and outside surface of the chimney section 1 are covered with a glass frit. v The frit is normally applied as a slurry. 'The chimney section 1 is then transferred to a drying station 9 where the moisture in the slurry is driven off leaving the glass frit on the chimney section. The chimney section 1 is subsequently transferred to a firing station 10 where the section 1 is heated to fuse the glass frit to the base metal. After the firing operation is completed, the chimney section 1 is transferred to a storage or assembly station 11. In some instances, it may be desirable to provide more than one coating of glass in which case the chimney section is taken from the firing station 10 and returned to the slushing station 8 where glass frit is again applied to the coated chimney section. The subsequent steps of drying and firing follow to complete the coating.

Referring to the illustrated firing station in Fig. 3, an induction heating coil 12 is disposed within a pit 13 which is disposed below ground level. The induction coil 12 is adapted to be moved vertically out of the pit and through a chimney section 1 which is disposed over the pit and which is axially aligned with the coil. The coil 12 is provided with a diameter just slightly less than the inner diameter of the chimney section to provide close coupling between the coil and chimney section 1. Consequently, the alignment of the chimney section 1 over the coil 12 is relatively critical.

The chimney section 1 is supported in a vertical position on a charging car 14 by a plurality of leveling pads 15 engaging the lower flange 3, as shown in Figs. 3 and 4. The leveling pads 15 are threaded into the charging car 14 to allow slight vertical adjustment and to thereby allow accurate leveling of the chimney section. Four horizontally adjustable brackets 16 are slidably secured in guideways 17 carried by the car 14 at degrees to each of the leveling pads 15. The brackets 16 each eugage the edge of flange 3 and are adjusted to precisely align the chimney section 1 over a central aperture 18 in the car 14. The car 14 is provided with a plurality of wheels 19 which run on tracks 20 disposed to either side of the pit 13 to accomplish movement of the car and chimney section 1 to and from the pit 13. A stop 21 is provided on each track 20 adjacent the pit 13 such that when the forward wheels 19 engage the stops 21 the chimney section 1 is precisely aligned above the induction heating coil 12. The heating coil may then freely move vertically through the car aperture 18' and the chimney section 1.

The induction heating coil 12 comprises a helically wound conductor bar 22 of copper or the like. The bar 22 is wound upon a plurality of vertically disposed Transite support members 23 and secured to bars 23 by bolts 24 which pass through the bar 23 and thread into the Transite member. As shown in Fig. 4, the Transite supports 23 are circumferentially spaced to provide a plurality of supports about the coil to maintain the separation of adjacent coil convolution or turns which tend ties required for a heating coil of this type.. The current carried by the coil 12*is relatively large and gencrates a high amount of heat within the helical bar. To carry away a substantial part of the heat, a cooling coil 25 is brazed or otherwise secured to the back or inside surface of the helical conductor bar 22 and rests within suitable recesses in the adjacent face of the Transite bars 23. The cooling coil 25 is connected at opposite ends to a pair of flexible lines 26 which are carried on a reel 27. As the coil 12 is vertically moved, the lines 26 wind and unwind upon reel 27. A water inlet 28 and a water outlet 29 are connected to the lines 26 at the reel 27 to circulate water through the coil 25.

A plurality of radially extended metal brackets 30 are rigidly connected one each to the ends of every other Transite support 23 and at the opposite end to a central post 31. Brackets 30 are formed of stainless steel or other non-magnetic material to prevent establishment of induced circulating currents. The center post 31 is connected to a flange 32 on the top of a vertically moving piston rod 33 which moves the coil 12 through the chimney section 1. The rod 33 is journaled within a stationary cylinder 34 to establish a fluid motor for vertically moving the coil 12.

A bracket portion 35 of cylinder 34 rests on the base of the pit 13 with the cylinder 34 extending into a reduced diameter extension 36 of the pit 13. A fluid inlet 37 is provided adjacent the lower end of the cylinder 34 and is connected to a source of fluid pressure, not shown, to provide the power for raising and lowering of the coil 12.

A pair of long bus bars 38 are longitudinally separated by suitable insulation 39 and are centrally secured to the piston rod 33 by a bracket 40. The bus bars 38 extend coextensively downwardly into the pit extension 36 and also upwardly to the coil 12. The upper ends of bus bars 38 are connected to opposite ends of the helical bar conductor 22 by suitable bolts 41 as shown most clearly in Fig. 4-. A plurality of current brushes 42 are supported in engagement with one or the other of the bus bars 38 by a bracket 43 which is secured to the base of pit 13. A pair of incoming power leads 44 are connected to the brushes 42 to establish current flow in the coil conductor 22.

During the firing operation wherein the glass coatings and 6 are fused to the chimney section, fluid pressure is applied to cylinder 34 and the coil 12 is first raised to the upper portion of the chimney section 1. The current is then turned on and the coil 12 moved slowly downwardly through the chimney section 1 to progressively heat successive areas of the chimney section. The coil 12 establishes an induced current in the chimney section 1 immediately adjacent the coil 12 and progressively heats successive areas of the chimney section. The induced current creates an extremely high heat area or band on the adjacent chimney surface suflicient to fuse the glass frit to the chimney section. For example, in the firing of two coats of glass, the firing of the first coat raises the temperature of the chimney section to 1620 F. and the firing of the second coat raises the temperature to Although the preceding temperatures do not melt the metal, they change the metal to a generally plastic state. As the coil 12 descends and heats the intermediate and lower portions of the chimney section 1, the weight of the chimney section above the heated section increases and eventually causes bulging of the metal. To relieve the lower portions of the chimney section 1 of a part of the entire weight above it, a flange gripping mechanism 45 is adapted to grip the upper flange 2 of the chimney section 1 and exert a lifting force on the chimney section. The gripping mechanism 45 is centrally secured to the top 46 of a housing 47 which encloses the pit 12 and the lifting mechanism 45.

As more clearly shown in Figs. 5 and 6, the lifting mechanism 45 comprises three radial arms 48 joined at one end between a lower plate 49 and an upper plate 50. The arms 48 are extended radially from the plates 49 and 50 and trisect a circle to equicircumferentially space the arms. An eyebolt 51 extends through the plates and is engaged by a hook 52 which is secured to one end of a flexible cable 53. The opposite end of cable 53 is secured to a piston 54 of a fluid motor 55. By suitable actuation of the fluid motor 55, the three arms 48 are simultaneously moved in a vertical direction.

Each of the three arms 43 is formed from a pair of back to back channel-shaped members which are disposed in horizontally spaced relation. A plurality of cross-rods 56 are secured to the upper surface of the channel members and bridge the space therebetween. Three vertically depending hangers 57 are pivotally supported one each on corresponding cross-rods 56 of each arm 48 in accordance with the diameter of the chimney section 1. Each hanger 57 is provided with a series of vertically spaced angular slots 58 adapted to engage a cross-rod 56. A plurality of slots 58 are employed to allow variations in the vertical positioning of lateral extensions 59 which are secured to the lower ends of hangers 57. The lateral extensions 59 extend inwardly toward the chimney section 1 and engage the lower surface of the upper flange 2 of the chimney sections 1 to transmit a lifting force on the flange and thereby counterbalance a portion of the weight of the chimney section. Upstanding pins 6%) on each projection 59 engage one of the apertures 4 in the flange 2 to prevent slipping of the hangers from the flange.

To allow movement of the chimney section into and out of the firing station, the hangers 57 are pivoted about the supporting cross bar 56 to rotate the lower ends 59 of the hangers from beneath the flange 2 as shown by the dotted position of the hangers in Fig. 3 and presently described. The fluid motor 55 is then actuated to raise the lifting mechanism 45 and remove the lower ends 59 of the hangers from the path of the chimney section 1. A link 61 is connected to the upper end of each hanger 57 and extends inwardly and downwardly to a rotating member 62 supported by the upper plate 49. Referring particularly to Fig. 6, the links 61 are secured to the rotating member 62 at a position intermediate the axis of arns 48. When the member 62 is rotated, the links 61 pull the top of the hangers 57 inwardly and downwardly and swing the lower end of the hangers 57 outwardly and upwardly. The rotating member 62 is rotated to pivot the hangers 57 by a fluid motor 63 which is secured to one of the arms 48 by a bracket 64. A reciprocating piston 65 is slidably journaled within motor 63 and is connected at the opposite end to the periphery of the member 62. Afluid connection 66 to the motor 63 alternately extends and retracts the piston 65 to rotate the member 62 and pivot the hangers 57.

As previously noted, the lifting mechanism 45 is preferably not actuated to counterbalance a portion of the weight of section 1 until the upper portion of the chimney section 1 has been fired and cooled. If the lifting action is applied while the upper end of the chimney section is still in a semi-plastic state, the flange 2 will most likely deform. Substantial weight only exists on the lower portions of the chimney section 1 and a lifting force is therefore only necessary while firing the uppermost portion of the section.

The lifting force applied by fluid motor 55 is adjusted by varying the incoming fluid pressure in accordance with the size and weight of the chimney section. For example, it was found in firing a 20 foot chimney section 1 of inch steel that if the force equal to onehalf the weight ofthe section 1 was applied when the heating coil 12 reached the central portion of the chimney section, bulging was prevented. The point or position of counterbalance will vary with the length of the section,

s arpen the wall thickness and similar factors effecting the weight above any particular heated area of the section 1.

In lifting on the chimney section 1, it is preferable that only a port-ion of the weight be counterbalanced because if the entire weight of the chimney section is taken up, the section is lifted entirely off the base. The section may then shift and hit the heating coil 12 with disastrous damage to the coil and/or chimney section.

The present invention provides a method and apparams for glass coating long metal members without deforming the member during the glass coating process and thus permits the glass coating of heavy metal members such as chimney sections.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

I claim:

1. The method of firing progressive sections of a long metallic hollow article to fuse a corrosion protective coating to the article, which comprises applying said protective coating to said article and supporting the article on a base member during the firing operation, firing progressive areas of the member from the top down to a temperature at which the heated area is generally nonself-supporting to fuse the coating to said article, and a lifting force to the upper portion of the article, said force being sufiicient to take up a portion of the weight of the article resting on said base to prevent deformation when heated but not so great a lifting force as to effect deformation thereby.

2. The method of firing progressive sections of a long metallic hollow article to fuse a corrosive protective coating to the article wherein the fired metal is temporarily in a plastic state, which comprises applying said protective coating to said article while supporting the article to hold the article in a vertical position during the firing operation, firing progressive areas of the article from the uppermost coated portion downwardly to a temperature at which the heated area is generally non-self-supporting to fuse the coating to said article, and applying a lifting force to the upper portion of the article subsequent to firing and cooling of the upper portion of the article, said force being sutncient to take up a part of the weight of the article while the balance of the article is fired to prevent deformation of the article when heated but not so great a lifting force as to effect deformation thereby.

3. The method of firing progressive portions of a. tubular metal smokestack having upper and lower flanges to fuse a corrosive protecting glass coating to the vertical surfaces of the smokestack, which comprises applying a glass slurry to said smokestack, supporting the smokestack on a base member and firing progressive sections of the smokestack starting with the upper end at a temperature at which the heated area is generally non-self-supporting and descending to the lower end to progressively fuse the coating to the smokestack, and subsequent to the firing of a substantial portion of the smokestack applying a lifting force to the upper flange, said force being sufiicient to take up a portion of the weight of the smokestack during the firing of the bal-- ance of the smokestack to prevent deformation of the article when heated but not so great a lifting force as to efiect deformation thereby.

4. The method of firing progressive sections of a long metallic hollow article to fuse a corrosion protective coating to the article, which comprises applying said protective coating to said article and supporting the article on a base member during the firing operation, firing successive areas of the member from adjacent one end of the member to the other to a temperature at which the heated area is generally non-self-supporting to fuse the coating to said article, and applying a lifting force to the upper portion of the article, said force being sufiicient to take up a portion of the weight of the article at least during the period of heating of the lower portion of the article resting on said base to prevent deformation of the article when heated but not so great a lifting force as to effect deformation thereby.

References Cited in the file of this patent UNITED STATES PATENTS 303,817 Cross Aug. 19, 1884 1,733,006 Cook et al. -2 Oct. 22, 1929 1,836,444 Carnahan Dec. 15, 1931 2,281,334 Somes Apr. 28, 1942 2,361,976 Somes Nov. 7, 1944 2,382,779 Denneen et al. Aug. 14, 1945 2,393,484 Somes Jan. 22, 1946 2,399,896 Somes May 7, 1946 2,613,823 Johns Oct. 14, 1952 2,757,267 Brauer et al. July 31, 1956 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2 927 869 Richard Ma Hortvet hat error appears in the-printed specification orrection and that the said Letters March B 1960 It is herebfi certified t of the above numbered patent requiring 0 Patent should read as corrected below.

Column 5 line 27 for "and a read and applying a Signed and sealed this 29th day of November 1960o (SEAL) Attest: KARL H AXLINE ROBERT C. WATSON Commissioner of Patents Attesting Oflicer UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Noa 2,,927 869 March 8 1960 Richard M, Hortvet It is herebj certified that error appears in the-printed specification of'the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5, line .27 for and a" read and applying a o Signed and sealed this 29th day of November 19600 (SEAL) Attest:

KARL H. AXLINE ROBERT C. WATSON Commissioner of Patents Attesting Oflicer 

1. THE METHOD OF FIRING PROGRESSIVE SECTIONS OF A LONG METALLIC HOLLOW ARTICLE TO FUSE A CORROSION PROTECTIVE COATING TO THE ARTICLE, WHICH COMPRISES APPLYING SAID PROTECTIVE COATING TO SAID ARTICLE AND SUPPORTING THE ARTICLE ON A BASE MEMBER DURING THE FIRING OPERATION, FIRING PROGRESSIVE AREAS OF THE MEMBER FROM THE TOP DOWN TO A TEMPERATURE AT WHICH THE HEATED AREA IS GENERALLY NON-SELF-SUPPORTING TO FUSE THE COATING TO SAID 